Center



Nov. 29, 15k. J. H. SMITH 1,889,502

CENTER Filed Sept. 30, 1929 INVENTOR. J'Aqao J/v/W/ A T ORNEY.

Patented Nov. 29, 1932 UNITED STATES PATENT OFFICE CENTER Application filed Septemlnr a0, 1929. Serial No. 396,047.

This invention relates to centers, and has to do particularly with the structure and lubrication of a cone type dead center for lathe tail stocks and the like.

Although many different types of live centers have recently been adapted for commercial use, the plain cone type dead center is still used extensively where accurate results are required. WVhile dead centers are conducive to accurate precision work, they are open to the objection of wear and the necessity of frequent regrinding.

It is the object of the present invention to provide a very compact and simple center the locating and positioning portion of which is formed in the ordinary manner and preferably the ordinary materials but the working portion of which is formed of a very hard steel or alloy, and is insertable in the 99 main body of the center so as to form a unit therewith. I

Another feature of the present invention resides in the provision of a novel oil supply and oil groove whereby a constant film of oil 33 is maintained between the working surface of the center and the work itself.

In the drawing:

Fig. 1 is a frontelevation, partly in section,

' of one form of my novel center member.

33 Fig. 2 is an enlarged detail view of the insert formed of separate metal.

Fig. 3 is an enlarged fragmentary view of the body of the center, showing in particular the hole for receiving the insert and the 33 oil passageways.

Fig. 4 is an end view of the working end of the center.

In the embodiment illustrated in the drawing, the main body 1 of the center is shown 47 formed in the ordinary manner with a tapered shank 2, a head 3 and a cone shaped portion 4.

As best shown in Fig. 3 the cone shaped portion 4 instead of extending to a point, as

in the standard center, is rovided with an aperture 5 which prefera ly extends to a point within the head 3. An oil reservoir 6 is formed in what might be termed the top of the center and is provided with suitable threads 7 for receiving a suitable cup or oil supply means 8. A passageway 9 is formed between the aperture 5 and the well 6.

The main body 1 of the center is preferably formed of the same grade of metal that has heretofore been used in the past, although it will be obvious that the materials going to make up such main body 1 may be varied considerably due to the fact that no parts of such body are subject to any appreciable wear. The apex of the cone portion 4 of the center is completed by means of an insert 10. This insert is provided with a cone shaped outer end 11 corresponding to the cone shaped portion 4 of the main head and is also provided with a cylindrical body portion 12 preferably adapted to have a press fit relation with the aperture 5. The insert 10 may, of course, be brazed in place or any other means may be used for securing such insert in place.

The insert 10 is preferably formed of a relatively hard, wear resisting, material such as tungsten carbide, stellite, or other steels or alloys of this class. In its preferred form such insert 10 will not permit of interior machining and for this reason a conduit 13 is preferably molded or otherwise formed therein. This conduit is adapted to substantially register with the conduit 9 although this is not absolutely necessary in view of the recess 14 at the inner end of the apertures 5.

A suitable oil groove 15 is formed in the cone shaped surface formed by the combined surfaces 4 and 11, said groove preferably starting from the oil conduit 13 and extending upwardly towards the base of the cone. The groove 15 is preferably inlongitudinal alignment with the cup 8 and well 6 whereby oil will flow from the cup 8 through the connecting conduits 9 and 13 to the groove 15, whenever work is to be supported by the center.

The surface 11 of the insert 10 is preferably designed so as to form the sole bearing contact between the center and the work and in case that extra deep centers are used in certain classes of work, it will be understood that the depth of the surface 11 should 100 be correspondin 1y increased and the depth of the surface 4 ecreased.

The length of life of the center will dend upon the quality of materials used in 5 orming the insert 10, although it will be obvious that the complete cone surface of the center may be ground and trued up in the customary manner, the oil groove being deepened if necessary. It will be un- 10 derstood that the shape of the insert, the

location of the various oil grooves and the design of the center in general may be varied considerably.

It will thus be seen that I have provided 35 a center which provides all of the precision and accuracy obtained from the standard dead center but which presents a centering and supporting surface of Very hard, wear resisting, material. This material is very 29 expensive but by making substantially the entire body of a relatively inexpensive standard material and by making the work receiving surface part of a relatively small insert, combined with means for supplying a constant film of oil, the cost of the center is made only slightly more than that of standard cone shape centering tools.

What I claim is: 1. A center tool of the class described, comprising a shank and a cone shaped end portion of a material relatively easy to work, an aperture formed in the end of said cone shaped portion and having a countersunk end communicating with an oil conduit, a short insert formed of tungsten carbide shaped to fit and brazed within said aperture and hav ing a cone shaped portion on the end thereof for registering with the cone shaped portion in said main body, and an oil conduit formed in said insert for conducting oil from said first named conduit, through said insert, to the work receiving surfaces formed by said cone. 1 p 2. A center tool of the class described, comprising a'shank and a cone shaped end portion of a material relatively easy to work, an aperture formed in the end of said cone shaped portion and communicating with an oil conduit, a short insert formed of tungsten carbide shaped to fit within said aperture and having a cone shaped portion on the end thereof for registering with the cone shaped portion in said main body, a space between the other end of the insert and the end of said aperture and an oil conduit formed in said insert for conducting oil from said first named conduit and space, through said insert. to the work receiving surfaces formed by said cone, said conduit in said insert being positioned closely adjacent the axis of the tool whereby to conduct a lubricant to a point closely adjacent the apex of the cone.

3. A center tool of the class described. comprising a shank and a cone shaped end portion of a material relatively easy to work,

an aperture formed in the end of said cone shaped portion and communicating with an oil conduit, an insert formed of relatively hard, wear resisting, material shaped to fit within said aperture and having a cone 1" shaped portion on the end thereof for registering with the cone shaped portion in said main body, and an oil conduit formed in said insert for conducting oil from said first named conduit, through said insert, to the work receiving surfaces formed by said cone, said conduit in said insert being positioned closely adjacent the axis of the tool whereby to conducta lubricant to a point closely adjacent the apex of said cone, and an oil groove formed in the surface of said cone and connecting with said oil conduit whereby to conduct the oil outwardly towards the base of the'cone.

In testimony whereof I aflix my signature. 95

JOHN HUGO SMITH. 

